Furnace



(No Model.) 2 Sheets-Sheet 2.

O. J. DORRANCL.v

PURNAGE.

ANDREW E GRAHAM PHUTOUTHQWASMINGTONN.

UNTTED STATES PATENT OFFICE.

CHARLES J. DORRANOE, OF C-IIIOAGO, ILLINOIS.

FU RNACE.

SPECIFICATION forming part of Letters Patent No. 559,887', dated May 12, 1896.

Application tiled January 26,1892. Serial No. 419,255. (No model.)

,To all whom t may concern,.-

Be it known that I, CHARLES J. DORRANCE, of Chicago, in the county of Cook and State of Illinois, have invented certain new and useful Improvements in Furnaces; and I do hereby declare that the following is a full, clear, and exact description thereof, reference being had to the accompanying drawings, and to the letters of reference marked thereon, which form a part of this specification.

In boiler-furnaces as heretofore constructed the boiler has been generally arranged to extend the entire length of the furnace, its forward end being located above or forming the top wall of the fire-chamber of the furnace to receive the heat rising from the bed of fuel on the grate. lYhile this construction admits of economy of space, it has resulted in the formation of smoke, owing to the rapid cooling or condensation of the highly-heated gases on coming in contactpwith the cooler surface of the boiler, (which, as is well known, cannot be heated approximately beyond the temperature of boiling water under pressure) and the consequentfouling of the boiler-lines, thus reducing the heating capacity of a given charge of fuel and at the same time contaminating the surrounding` atmosphere.

The object of my invention is to effect a more perfect consumption of the products of combustion, thus increasing the heating capacity of the furnace and avoiding` the fouling of the boiler-flues, and this object is attained by the construction illustrated and now to be described.

The invention consists in the matters to be hereinafter described, and pointed out in the appended claims.

In the accompanying drawings, wherein is illustrated one form of steam-boiler furnace embodying my improvements, Figure l is a front elevation of the furnace and boiler. Fig. 2 is a similar view with the furnace-front removed. Fig. 3 is a vertical longitudinal r section through the furnace and boiler-setti ng. Fig. i is a transverse vert-ical section on the line l l of Fig. Fig. 5 is a sectional detail illustrating the shell or jacket for the top wall of the fire-chamber and one form of damper for closing the air-inlets thereto.

In said drawings the letter A is used to designate the lire-chamber; B, the combustionchamber, O, the bridge-wall interposed between the lire and combustion chambers, and D the boiler arranged above the combustionchamber.

The fire-chamber A comprises a fire-front a, side walls a', and a top or roof wall a2 of fire-brick or other suitable refractory material. The roof-wall is supported on the side walls and is arched transversely to present a surface which will reflect, radiate, or reverberate heat toward the longitudinal center of the fire-chamber,thus subjecting the products of combustion rising from the bed of fuel upon the grate E to the heat radiated from the walls a and CL2 of the fire-chamber as well as the heat rising from the incandescent fuel, whereby the gaseous or lighter particles will be consumed before their escape from the fire-chamber A into the combustion-chamber B.

The grate E is preferably downwardly inclined from front to rear to insure a more even supply of air to and through the gratebars at all points, and should be of a construction to admit of the supply of a great volume of air to the bed of fuel thereon. As fuliilling these requirements, I have shown the furnace fitted with a Dorrance grate consisting of a supporting-frame e, on which are mounted rocking bars or plates e', such as shown in Letters Patent No. tOi-3,255, issued May ll, 188i). Other suitable grates may, however, be used.

The bridge-wall O rises vertically from the ash-pit A to a point parallel with the rear end of the grate E, from whence its front face c is inclined rearward at an angle, terminating in a straight horizontal crest c. rlhe rear or inner face c2 of the bridge-wall is inclined downward at right angles to the front face c.

In the furnace illustrated the roof or top n2 of the fire-chamber is constructed in the form of a semicircular arch, its radial center being somewhat above the center of the grate, as best shown in Fig. 2. I, however, do not wish to confine myself to this particular form of arched top a2, as the arch maybe in a different are, the radial center of which may be at or below the center of the grate, the essential feature being a structure in which heat will be radiated from its walls iu converging lines IOO tending toward the center of the bed of fuel upon the grate, thus subjecting' the products of combustion rising from the fuel to the heat radiated from the intensely-heated walls of the fire-chamber, as well as to the heat from the incandescent fuel, whereby the combustible atoms released from the fuel by the heat of the fire are entirely consumed within the fire-chamber.

The arched top d2 of the fire-chamber is shown as inclined downward toward the rear and extending beyond the bridge-wall, the effect of this construction being to emphasize the reverberatory action of the top wall ai), and to gradually.contract the area of the firechamber from the front thereof to the bridgewall, which latter, in conjunction with the arched top CL2, forms a narrow throat or gorge at the rear of the fire-chamber, through which the products of combustion pass on their way to the heating or combustion chamber B, and will be so intimately commingled as to insure t-he consumption of any atoms or particles that may have escaped combustion above the grate.

Owing to the more perfect combustion in the fire-chamber, the heated gases brought into contact with the cooler surface of the boiler in the combustion-chamber will be free, or practically so, from smoke-form ing particles, so that the cooling or condensation of said gases will not result in the deposit of soot or smokelin the heating-chamber orboiler-fiues, thus maintaining the normal heat-ing capacity or area of said [i ues through a greater period of time than heretofore and avoiding the dis# charge of smoke from the chimney. It has been usual heretofore to lay the bot-tom wall B/ of the heating or combustion chamber B, where such a wall has been used, directly upon the ground, and this gives risc to the attraction of moisture from the ground, as is evidenced by the moisture of the ashes lodging in the combustion-chamber, the presence of such moisture necessarily reducing the temperature of the heated gases flowing through the combustion-chamber. lVith a view to utilizing to the greatest extent the heat passing through said combustion-chamber, the latter is lined with a refractory flooring B', so arranged as to leave a dead-air space or spaces B2 beneath it to prevent the absorption of moisture by the material of said flooring. This end may be attained bylayin g the flooring B upon a bed of coarse rubble; but I prefer the arrangement shown, wherein tiles Z2 are supported at their meeting edges or corners upon suitable foundations U, orto employ hollow fireproof tiles in the construction of said flooring. This flooring is curved or dished transversely in an arc having its radial center at or somewhat above the longitudinal center of the boiler, as shown in Fig. et, in order that heat may be radiated therefrom toward the boiler, and in most instances I contemplate using glazed tiles b, or

those having a vitreous surface, for the double purpose of reflecting the heat toward the boiler and the more certain avoidance of absorbing moisture. The boiler-setting F is of usual construction, except that at the rear it is drawn down or built in to counteract the tendency of the heat to ascend to the upper flues of the boiler and to direct the flame and heated gases toward the lower fiues thereof, as is best illustrated in Figs. 3 and f. In these figures the side walls f of the combustion-chamber are shown bricked in a number of courses at the rear to attain this end, and in Fig. et the rear wall f is brieked in against the end of the boiler a number of courses below the top of the boiler-shell. I have also shown the rear wall f fitted at a suitable distance above the lower edge of the boiler with a deflector F, the purpose of which is to di-` rect aportion of the heat and flame into thelowermost fines of the boiler.

In the practical use of a furnace constructed as herein described-that is to say, one in which the re-chamber is located in advance o of the boiler-a certain small percentage o heat will be radiated from the arch a? of the fire-chamber into the furnace-room. To avoid this loss of heat by radiation and the overheating of the furnace-room, the top o2 of the 9 5 fire-chamber may be inclosed by a shell or` jacket G, of iron or other suitable material, so constructed and arranged that there will be an air-space g between the exterior of the wall a? and the jacket G. This jacket may 10o also be covered with an envelop G, of asbesf tos or other non-conductin g material, to more effectually prevent the radiation of heat.

I have found by experience that in rapid firing with some varieties of coal which are` particularly rich in free carbon the volume i of free carbon released is so great in proportion to the grate-surface that sufficient air cannot be drawn through the grate to supply complete combustion, and therefore a portion 1 1o of the free carbon or smoke-formingparticles" will pass from the fire-chamber A unconsumed. To provide for such contingencies I have supplied the front and the arched top of the fire-chamber with a number of minute` air-inlets a3 a", which are normally closed by i means of danipers (t5 and a5. The air-inlets as are formed in the adjacent side plates Al2 of the fire-doors and in a connecting-plate AS bridging the space between the inner ends of 12o said adjacent side plates of the fire-doors. A damper ai slides in vertical ways formed in the iron furnace-front between the fire-doors, thus constituting a closed chamber A5, the inner and side walls of which are formed by the perforated plates A2 and A3. The damper may be secured in different positions of adjustment by any well-known means-as, for instance, by the counterweight shown. The air-inlets c are formed in the arched top 13: of the fire-chamber at apoint adjacent to the bridge-wall, and are normally closed by a damper arched to conform to the arch of said top wall. The outer ends of these inlets are inclosed by the jacket G, so that air supplied through them to the firechamber is first heated in the space between the arched top wall a2 and its jacket. In order that air may also be drawn from this space to supply the inlets er at the front of the iirechamber, a passage may be formed between said space and the chamber A5, said passage being normally closed by any suitable damper to prevent the admission of air through the inlets c? under ordinary conditions. Passages or tlues A6 may also lead from this space between the top wall a2 of the fire-chamber and its jacket G to the sides of the ash-pit in order to supply heated air beneath the grate. To afford an air-supply to said space g the jacket G is provided at its lower edges with openings g', tted with damper-s, by means of which said openings may be closed under ordinary conditions, and thus the space g then becomes or constitutes a dead-air space.

XVhile I do not wish to be limited to the details of construction herein shown and described, yet I have found that the most practical results are attainable bythe use of this construction.

I iind very great advantages derived by providing the under side of the arched top and side walls of the ire-chamber with a glazed or vitrified surface; but while claiming this feature I do not wish to be limited thereto, as the arched tcp may be constructed as first described.

I have thus far described my improvement in furnaces as applied to a boiler but it must be understood that I do not intend to limit myself to this single application, inasmuch as it may be used, with very slight mechanica-l changes, in constructing smelting,refin ing, copper-matte, puddling, and other furnaces. It will also be understood that the front of the boiler may overlap the arched top of the fire-chamber to a greater extent than is shown herein, so long as said boiler does not form any part of the walls of the iirechamber, the essential feature of this part of the invention being that the temperature of the lire-chamber or the heated products of combustion therein shall not be reduced by exposure to or contact with the cooler surface of the boiler forward of the bridgeavall.

l. A boiler-furnaee comprising a {ire-chamber and a combustion-chamber separated by a bridge-wall, said fire-chamber being arranged in advance of the boiler and having its side and top walls formed of a continuous arch, said top wall being rearwardly inclined and extended beyond the crest of the bridgewall and beneath the boiler7 substantially as described.

2. Aboiler-furnace comprisinga iire-chamber arranged in advance of the boiler and having its side and top walls formed of a continuous arch, said top being rearwardly inclined and extended beneath the boiler, a combustion-chamber beneath the boiler, and a bridge-wall the crest of which is arranged somewhat forward of the rear end of the arched top of the fire-chamber and forms in connection therewith a relatively narrow throat or gorge between the fire and combustion chambers, substantially as described.

3. A boiler-furnace comprisinga fire-chamber arranged in advance of the boiler and provided with a rearwardly-inclined arched top extending beneath the boiler, a combustion-chamber beneath the boiler having a transversely-concaved bottom wall or iiooring, and a bridge-wall between said fire and combustion chambers and in advance of the rear end of the arched top of the fire-chamber, substantially as described.

4. The combination with a boiler-furnace comprising a lire-chamber arranged in advance of the boiler and having an arched top extending beneath the boiler, and a combustion-chamber beneath the boiler, of a jacket arranged to cover the arched top wall of the fire-chamber and leave an air-space between said jacket and top wall, substantially as described.

5. The combination with a boiler-furnace having a fire-chamber arranged in advance of and having its arched top extending be neath the boiler, and a combustion-chamber beneath the boiler, of a jacket inclosing the top wall of the fire-chamber forward of the boiler and provided with valved openings, and ducts or inlets leading from the air-space between the jacket and top wall, to the interior of the 'fire-chamber, substantially as described.

G. The combination with a boiler-furnace comprising a re-chamber arranged in advance of and having an arched top wall extending beneath the boiler, and a combustion-chamber beneath the boiler, of a jacket inclosin g the upper part of the top wall of the tire-chamber and having valved openings therein, and valved inlets leading from the air-space within the jacket to the interior of the fire-chamber, substantially as described.

7. The combination with a boiler-furnace comprising a fire-chamber arranged in advance of and having a top wall extending beneath the boiler, and a combustion-chamber beneath the boiler, of a jacket inclosing the upper part of the fire-chamber, said jacket being provided with valved openings, valved inlets leading from the air-space beneath the jacket to the interior of the fire-chamber, and passages leading from said air-space to the ashpit beneath the grate, substantially as described.

S. A boilerfurnace comprising a lire-chainber and a combustion-chamber separated by a bridgeswall, said fire-chamber being ar- IOO IIO

ranged in advance of the boiler and provided my invention I a-fx my signature in presence with arearwardly-inciined arched top extendof two Witnesses.

inn beneath the boilerbeyond the crest of the Y T 1 bridge-Wall, said arched top being provided CHARLES J DORRAB CE' 5 with L glazed or vitricd under surface, suh- Vitnesses:

starntiztlly its described. TAYLOR E. BROWN,

In testimony that I claim the foregoing its GEORGE XV. HIGGINS, Jr. 

